Sharp pointed bits are driven mechanically and forcefully into the material to be mined or cut. These bits have a mounting shank and a coaxial working end usually fitted with a hard material such as a high grade of tungsten carbide. The mounting shank is received in an open-ended hole in a mounting block with a loose fit which allows the shank and bit to rotate as it is cutting, thus equalizing the tip wear. The mounting block is one of a series which are located in spaced relation on a revolving wheel or an endless chain which are mechanically driven in the area of the material to be mined or cut.
It is important that the bits be so mounted that the detritus from the cut material will not clog the mount to prevent rotation of the bits. The bits usually have an annular groove in the mounting end of the bit located so that the groove extends outwardly of the back end of the hole in the mounting block. A retaining ring can then be installed in the groove having a diameter larger than the hole in the block so that the bit will not leave the hole until the retainer is removed.
Various types of retainers have been used to retain bits of this type including split lock-washer type retainers, hair pin type wire retainers with spaced legs curved to encircle the groove in the bit, and hose clamp types with crossed arms which are squeezed together to enlarge the circular retainer portions for installation and removal.
It is an object of the present invention to provide a retainer which is easy to install and remove and which has a long wear life. It is a further object to provide a retainer which will absorb the shock of operation of the bits and prevent deformation of the bits which will interfere with removal. A still further object is the providing of a retainer which will freely spin and move axially on the bit during cutting operation. A still further object is to provide a retainer that can be easily installed and removed by hand, using pliers, screw driver or other suitable tools.
Another object is the provision of a hub extension or neck portion on the retainer which faces the hole of the mounting block and which will enter and lock in the block while not interfering with the rotation of the bit. An additional object of the present invention is to provide a retainer that is shock absorbent and reduces noise levels during operation.
Other objects and features of the invention will be apparent in the following description and claims in which the principles of the the invention are set forth together with details which will enable persons skilled in the art to practice the invention, all in connection with the best modes presently contemplated for the invention.